Old Gumphrey said:
While the "nobody-with-good-strength" is certainly possible, I think I've run one game where somebody didn't have a hulking melee destroyer with more than enough strength to carry 15 lbs. of gnome gear...and when is teamwork considered poor policy? Plus why don't people buy a stupid Haversack?
It costs a lot of points to get a score above 14 though. A medium character with a 14 strength can hold 58 lbs before going into medium load.
Greatsword 8 lbs
Longsword + heavy wooden shield 14 lbs
Chain shirt 25 lbs
We are already up to 33 to 39 lbs and we have not even gotten a good fraction of the amount of gear a normal adventurer would want to have handy and this could easily be the strongest guy in the party!
If we assume that he started at 15 and then put a point into it at level 4, which is a pretty good assumption I think, then his light load extends up to 76 lbs for a light load which is a lot more helpful.
Even with that though once we take into account things like backpack (2 lbs), bedroll (5 lbs), silk rope 50' (5 lbs), climbing gear (5 lbs), sunrods (1 lb each, 6 is a good number to have on hand, even with an everburning torch), everburning torch (1 lb), alchemist fire/acid/holy water/thunderstone (1 lb each, good to have several of each), tanglefoot bag (4 lb each, just too good, 1 or 2 on hand as necissary is great), a spare weapon or two (1 - 22 lb), food (who knows), and whatever else even that guy might not have all that much extra carrying capacity.
We have a 16 strength barbarian in our party and he carries extra things that we find along the way pretty often. But, he likes to stay in medium load or less whenever possible which also means considering when he comes out of rage during combat and his strength drops to 14. Between his normal gear and a few odds and ends that we pick up now and then that puts him right at that edge and sometimes over, he just does not have the extra weight capacity to hold another persons stuff for them without getting the bigger penalties. Yes, he has come out of rage in quite a few combats so far by the way.
As far as the haversack goes though, it is a great item but your party might not have the money for it or might not have the ability to get one. I think that the earliest reasonable time that a party might start to have one or two is between levels 5 and 6 but even then if it is a choice between a ring of deflection +1 or the haversack people might go for the extra armor class. I think that every party that does not wish to have a pack mule or carts or something should pool money together to get one though as it solves a lot of problems, although whoever carries it must still contend with its 5 lbs of weight and those that are most likely to want to use it during combat often tend to be those who have the lower strength scores in my experience. Luckily, at small with about strength 10 or medium with about strength 12 that is not a problem though.